Cold Finger Test

What is it?

The principle of the Cold Finger instrument is an inverted pipeline. The cooled metal finger replicates the inner wall of a pipeline. The heated and stirred oil flows around it. When the finger’s temperature falls below the Wax Appearance Temperature (WAT), wax starts to deposit on its surface. 

Why do we use it?

We use the cold finger test to calculate the efficiency of wax inhibitors. As the piece of equipment replicates a pipeline environment, the results we obtain are transferable to how our products would work in field conditions. Image result for cold finger test wiki
Our wax inhibitors are crude oil specific. They work via a lock and key mechanism whereby a specific paraffin inhibitor combines with a specific crude oil to prevent wax formation.

How does it work?

The paraffin test involves the immersion of a series of tubes in molten crude oil. The temperature of the tubes is set colder than the oil, such that waxes from the oil can deposit on the cool surfaces. The wax deposits are then weighed. With the addition of an effective paraffin inhibitor, the weight of the deposits should decrease and is presented as a percentage of wax inhibition. 

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A cold finger is a piece of laboratory equipment that is used to generate a localized cold surface. It is named for its resemblance to a finger and is a type of cold trap. The device usually consists of a chamber that a coolant fluid (cold tap water, or perhaps something colder) can enter and leave. Another version involves filling the device with a cold material (examples: ice, dry ice or a mixture such as dry ice/acetone or ice/water).

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Typically a cold finger is used in a sublimation apparatus, or can be used as a compact version of a condenser in either reflux reaction or distillation apparatus. Many commercially available rotary evaporators can be purchased with a cold finger in place of a Dimroth condenser, for example. When used as a condenser in a rotary evaporator, cold fingers can be cooled to a lower temperature of −78 °C (dry ice), compared with water condensers that can be cooled to −40 °C (ethylene glycol/water mixture). The lower temperature achieved reduces the quantity of volatile material exhausted into the air.

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